wacom: do not use relative data when exporting

we already are keeping a record of the x,y and p. So we are trying
to duplicate the effort by using new_rel.
The problem is that some reports have relative coordinates but absolute
pressure data. Which means we are missing the pressure change as it has
a relative value of 0.

By trusting the wacom internal state, we can have the json data that
matches it completely.

tuhi/wacom.py

@@ -773,8 +773,6 @@ class WacomProtocolBase(WacomProtocolLowLevelComm):
 
         drawing = Drawing(self.device.name, (self.width, self.height), timestamp)
 
-        have_abs = 0x00  # bitmask 3-bits: pyx
-
         while offset < len(data):
             packet = WacomPacket(data[offset:])
             logger.debug(f'packet: {packet}')
@@ -808,24 +806,7 @@ class WacomProtocolBase(WacomProtocolLowLevelComm):
             if packet.bitmask & 0b00111100 == 0:
                 continue
 
-            if not xrel:
-                have_abs |= 0x1
-            if not yrel:
-                have_abs |= 0x2
-            if not prel:
-                have_abs |= 0x4
-
-            if xrel or yrel or prel:
-                if not stroke.points:
-                    if have_abs == 0x7:
-                        logger.info('Forcing first point to be absolute')
-                        stroke.new_abs((x, y), p)
-                    else:
-                        logger.warning('First point in stroke is relative, skipping')
-                    continue
-                stroke.new_rel((dx, dy), dp)
-            else:
-                stroke.new_abs((x, y), p)
+            stroke.new_abs((x, y), p)
 
         drawing.seal()
         return drawing